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Polars again

  • Thread starter iamwilson
  • Start date
  • #1
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1. Homework Statement

A.Using polar coordinates, evaluate the improper integral of e^(-10(x^2+y^2))dxdy
B. use part A to integrate from negative infinity to positive infinity of e^(-10x^2)dx

2. Homework Equations [/b]



3. The Attempt at a Solution

i got part A to be pi/10, but for part B i clueless, can someone please give me a hit on how to integrate it!
 

Answers and Replies

  • #2
Dick
Science Advisor
Homework Helper
26,258
618
pi/10 looks ok. But for the second part you aren't supposed to do another integration. You are supposed to realize the first integral can be split into the product of a dx integral and a dy integral both of which look the same. Use exp(-10(x^2+y^2))=exp(-10x^2)*exp(-10y^2).
 

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